| Cause | Method of elimination |
| The indicator lamp lights up with the engine running at half or full brightness | |
| Carbon brushes are faulty | Replace brushes Replace the rotor |
| The rotor winding is faulty | Check cable connections |
| The excitation chain is broken | Check diodes and holders, replace if necessary |
| Faulty diodes or diode holders Cable D+/61 closes to "ground" | Fix the short circuit or replace the cable |
| The drive belt is loose | Tighten the belt Replace the regulator |
| The regulator is faulty Open or short to ground in the supply wiring | Check the cables and their connections |
| The control lamp does not light when the engine is started | |
| The control lamp is faulty | Install a 4W test lamp |
| Wire break | Fix the break |
| The indicator lamp does not light when the engine is not running. The ignition is on | |
| The control lamp is faulty | Install a 4W test lamp |
| The battery is discharged | Charge the battery |
| Battery faulty | Replace the battery |
| The cable is loose or damaged | Replace the cable, secure the connections |
| The regulator is damaged | Replace the regulator |
| Short circuit of the positive diode in the generator | Disconnect the wire otherwise the battery will discharge Rebuild the generator |
| The carbon brushes are worn out | Replace the brushes |
| Oxidation of slip rings, break in rotor winding | Repair the generator |
(The article text was copied from an online resource: «BMWman.ru»)